Do not use rails_config

[jandudulski]

We are using it for a while and we know that it is very unstable (most of last versions doesn't work at all...). For sensitive config use figaro instead. I'm not sure what should we use for global settings and which could be commit into repo.

At least we can put such values into application.yml.example files.

/cc @chytreg @teamon @Ostrzy @szajbus @sheerun @jcieslar

[teamon]

For settings stored in repository we could simply use env-name.rb files and config.foo = "bar".

@teamon uses build-in rails configuration, it's super effective!

[chytreg]

Agree with @jandudulski and @teamon

[sheerun]

ok

[teamon]

@jandudulski Please make PR